TWI875619B - Packaging glue and packaging film - Google Patents

Abstract

The encapsulation film of the present invention is formed by a photocuring reaction of the encapsulation adhesive of the present invention comprising a crosslinking polymer, an acrylate component and a photoinitiator. The crosslinking polymer is formed by a crosslinking reaction of a fluoroethylene-vinyl ether copolymer and a tetracarboxylic dianhydride. The fluoroethylene-vinyl ether copolymer has a weight average molecular weight of 10,000 to 50,000 and a hydroxyl value of 40 to 170 mg KOH/g. The tetracarboxylic dianhydride has The structure of R represents a tetravalent group containing fluorine and an aromatic group. The acrylate component includes at least one acrylate monomer selected from the group consisting of a monoacrylate monomer, a monomethacrylate monomer, a diacrylate monomer, a dimethacrylate monomer, a triacrylate monomer, and a trimethacrylate monomer. The present invention uses a packaging glue to make the packaging film have low water vapor permeability and not react with calcium titanium.

Description

Packaging glue and packaging film

The present invention relates to a packaging film, in particular to a packaging film for calcium-titanium solar cells.

Since calcium-titanium solar cells are easily affected by environmental factors such as humidity, which results in a short service life, a packaging film is generally provided in the structure of calcium-titanium solar cells to minimize the effect of humidity on calcium-titanium solar cells, so as to extend the service life of calcium-titanium solar cells. A good packaging film must not only have low water vapor permeability (WVP), but also must not react with the calcium-titanium in the calcium-titanium solar cell.

Therefore, the first object of the present invention is to provide a packaging glue that enables the packaging film to have low water vapor permeability and does not react with calcium titanium.

Therefore, the encapsulant of the present invention comprises a crosslinking polymer, an acrylate component and a photoinitiator. The crosslinking polymer is formed by crosslinking a fluoroethylene-vinyl ether copolymer and a tetracarboxylic dianhydride, wherein the fluoroethylene-vinyl ether copolymer has a weight average molecular weight in the range of 10,000 to 50,000 and a hydroxyl value in the range of 40 mg KOH/g to 170 mg KOH/g, and the tetracarboxylic dianhydride has In the structure shown in FIG. 1 , R represents a tetravalent group containing fluorine and an aromatic group. The acrylate component includes at least one acrylate monomer selected from the group consisting of a monoacrylate monomer, a monomethacrylate monomer, a diacrylate monomer, a dimethacrylate monomer, a triacrylate monomer, and a trimethacrylate monomer.

Therefore, the second object of the present invention is to provide a packaging film with low water vapor permeability and no reaction with calcium titanium.

Therefore, the packaging film of the present invention is formed by the above-mentioned packaging glue undergoing a photocuring reaction.

The effect of the present invention is that: through the mutual cooperation of the cross-linked polymer and the acrylate component in the encapsulation glue, the encapsulation film formed by the encapsulation glue will not react with calcium-titanium and has low water vapor permeability, so that the calcium-titanium solar battery containing the encapsulation film can have a long service life.

The packaging film of the present invention is formed by the light curing reaction of the packaging adhesive of the present invention, and the packaging adhesive comprises a cross-linked polymer, an acrylate component and a photoinitiator. The packaging film is suitable for application in calcium-titanium solar cells.

The cross-linked polymer is formed by cross-linking a fluoroethylene-vinyl ether copolymer with tetracarboxylic dianhydride.

The term "fluoroethylene" includes, but is not limited to, fluorinated ethylene such as tetrafluoroethylene or chlorotrifluoroethylene. The term "fluoroethylene-vinyl ether copolymer" refers to a polymer formed by copolymerization of fluorinated ethylene and an ether compound having a vinyl group. The weight average molecular weight of the fluoroethylene-vinyl ether copolymer ranges from 10,000 to 50,000. The fluoroethylene-vinyl ether copolymer has a hydroxyl group, and the hydroxyl value of the fluoroethylene-vinyl ether copolymer ranges from 40 mg KOH/g to 170 mg KOH/g. In certain embodiments, the fluoroethylene-vinyl ether copolymer is selected from at least one of the group consisting of tetrafluoroethylene-vinyl ether copolymers and chlorotrifluoroethylene-vinyl ether copolymers. In certain specific examples, the fluoroethylene-vinyl ether copolymer is selected from tetrafluoroethylene-vinyl ether copolymers. The commercially available products of the fluoroethylene-vinyl ether copolymer are, for example but not limited to, ^ZEFFLE® GK570 of DAIKIN, Japan, or ^LUMIFLON® LF-600X, ^LUMIFLON® LF-9716, ^LUMIFLON® LF-9721, ^LUMIFLON® LF200, LUMIFLON® LF200, ^LUMIFLON® LF200F, ^LUMIFLON® LF710F, ^LUMIFLON® LF910LM or ^LUMIFLON® LF916F of AGC, Japan. The commercially available products can be used alone or in combination. In certain embodiments, the commercially available products of the fluoroethylene-vinyl ether copolymer are selected from at least one of the group consisting of ^ZEFFLE® GK570 of DAIKIN, Japan and ^LUMIFLON® LF200 of AGC, Japan. In certain specific examples, the commercially available product of the fluoroethylene-vinyl ether copolymer is selected from ^ZEFFLE® GK570 of DAIKIN of Japan.

The tetracarboxylic dianhydride has In the structure shown in FIG. 1 , R represents a tetravalent group containing fluorine and an aromatic group. In certain embodiments, the tetracarboxylic dianhydride is selected from At least one of the group consisting of (hereinafter referred to as FIDA for ease of description) and 4,4′-(hexafluoroisopropylidene)diphthalic anhydride [4,4′-(Hexafluoroisopropylidene)diphthalic anhydride, abbreviated as 6FDA]. In certain embodiments, the tetracarboxylic dianhydride is selected from FIDA.

The usage ratio of the fluoroethylene-vinyl ether copolymer and the tetracarboxylic dianhydride is not particularly limited and can be any ratio. In certain embodiments, the usage of the fluoroethylene-vinyl ether copolymer and the tetracarboxylic dianhydride is adjusted according to the total amount of hydroxyl groups of the fluoroethylene-vinyl ether copolymer and the total amount of anhydride groups of the tetracarboxylic dianhydride, for example but not limited to, the molar ratio of the hydroxyl groups of the fluoroethylene-vinyl ether copolymer to the anhydride groups of the tetracarboxylic dianhydride is in the range of 0.5 to 2. In certain specific examples, the molar ratio of the hydroxyl groups of the fluoroethylene-vinyl ether copolymer to the anhydride groups of the tetracarboxylic dianhydride is 1.

The reaction conditions of the crosslinking reaction are, for example, but not limited to, carried out at a temperature of 75° C. in a nitrogen atmosphere. In some embodiments, the crosslinked polymer is formed by crosslinking a copolymer solution comprising the fluoroethylene-vinyl ether copolymer and an anhydride solution comprising the tetracarboxylic dianhydride. The copolymer solution also includes a solvent for dissolving the fluoroethylene-vinyl ether copolymer, such as, but not limited to, ethyl acetate. The anhydride solution also includes a solvent for dissolving the tetracarboxylic dianhydride, such as, but not limited to, ethyl acetate. Therefore, a polymer product obtained by the crosslinking reaction not only includes the crosslinked polymer, but also includes a solvent for dissolving the fluoroethylene-vinyl ether copolymer, and a solvent for dissolving the tetracarboxylic dianhydride.

The acrylate component includes at least one acrylate monomer selected from the group consisting of monoacrylate monomers, monomethacrylate monomers, diacrylate monomers, dimethacrylate monomers, triacrylate monomers, and trimethacrylate monomers. In certain embodiments, the acrylate monomer is selected from at least one of the group consisting of 2-phenoxyethyl acrylate (PEA), 1H,1H,7H-dodecafluoroheptyl acrylate (12FHA), neopentyl glycol diacrylate (NPGDA), 1,6-hexanediol diacrylate (HDDA), and trimethylolpropane triacrylate (TMPTA). In some embodiments, the acrylate component is composed of a single acrylate monomer; in some specific examples, the acrylate monomer is NPGDA or HDDA. In some embodiments, the acrylate component is composed of two or more acrylate monomers mixed in any proportion, for example, the acrylate component is composed of NPGDA and 12FHA mixed in any proportion, or the acrylate component is composed of NPGDA and HDDA mixed in any proportion, or the acrylate component is composed of 12FHA and HDDA mixed in any proportion.

The usage ratio of this crosslinked polymer and this acrylate component does not need special restriction, can be arbitrary ratio.In some embodiments, take the total amount of this crosslinked polymer and this acrylate component as 100wt%, the usage range of this crosslinked polymer is 20wt% to 80wt%, and the usage range of this acrylate component is 20wt% to 80wt%.In some specific examples, take the total amount of this crosslinked polymer and this acrylate component as 100wt%, the usage range of this crosslinked polymer is 30wt%, and the usage range of this acrylate component is 70wt%.

In some specific examples, the acrylate monomer of the acrylate component is NPGDA or HDDA, and the total amount of the crosslinked polymer and the acrylate component is 100wt%, and the amount of the acrylate monomer is 70wt%, and the encapsulation film has a lower WVP value and a higher visible light transmittance. In some specific examples, the acrylate component is a combination of HDDA and 12FHA, and the total amount of the crosslinked polymer and the acrylate component is 100wt%, and the amount of HDDA ranges from 50wt% to 65wt%, and the amount of 12FHA ranges from 5wt% to 20wt%, and the encapsulation film has a lower WVP value and a higher visible light transmittance. In some specific examples, the acrylate component is a combination of NPGDA and HDDA, and based on the total amount of the crosslinked polymer and the acrylate component as 100wt%, the amount of NPGDA used ranges from 17.5wt% to 52.5wt%, and the amount of HDDA used ranges from 17.5wt% to 52.5wt%, and the encapsulation film has a lower WVP value and a higher visible light transmittance. In some specific examples, the acrylate component is a combination of NPGDA and 12FHA, and based on the total amount of the crosslinked polymer and the acrylate component as 100wt%, the amount of NPGDA used ranges from 50wt% to 65wt%, and the amount of 12FHA used ranges from 5% to 20wt%, and the encapsulation film has a higher visible light transmittance.

The photoinitiator is used to make the crosslinked polymer and the acrylate component undergo the photocuring reaction under illumination. The photoinitiator is, for example but not limited to, a known or common photoinitiator such as 1-hydroxycyclohexylphenyl ketone. In some specific examples, the photoinitiator is 1-hydroxycyclohexylphenyl ketone. The amount of the photoinitiator does not need to be particularly limited and can be flexibly adjusted according to the amount of the crosslinked polymer and the acrylate component.

In some embodiments, since the polymer contains a solvent, the solvent can be removed at any stage in the process of preparing the encapsulant so that the encapsulant is substantially solvent-free. In some specific examples, the polymer, the acrylate component and the photoinitiator are mixed and then the solvent is removed.

In some variations of the present invention, the encapsulant further comprises an organic-inorganic composite material selected from at least one of the group consisting of modified silica nanoparticles and acryl silica microparticles.

The modified silica nanoparticles are formed by surface modification of silica nanoparticles by acrylalkoxysilane. In some embodiments, the acrylalkoxysilane is selected from at least one of the group consisting of monoacrylalkoxysilane, monomethacrylalkoxysilane, diacrylalkoxysilane and dimethacrylalkoxysilane. In some embodiments, the acrylalkoxysilane is selected from monoacrylalkoxysilane; in some specific examples, the monoacrylalkoxysilane is selected from 3-(methacryloxy)propyltrimethoxysilane (3-methacryloxypropyltrimethoxysilane, referred to as MPS). The average particle size of the silica nanoparticles is, for example but not limited to, 25 nm. The dosage ratio of the acrylalkoxysilane and the silica nanoparticles does not need to be particularly limited and can be any ratio. The specific preparation steps of the modified silica nanoparticles include subjecting the acrylalkoxysilane to a suspension containing the silica nanoparticles for a modification reaction, wherein a composite additive obtained by the modification reaction contains not only the modified silica nanoparticles but also the dispersion medium. The dispersion medium in the suspension is, for example but not limited to, methanol. The content of the silica nanoparticles in the suspension is, for example but not limited to, 40 wt%. The reaction conditions of the modification reaction are, for example but not limited to, being carried out at a temperature of 50° C. in a reflux system.

The acryl silica particles are formed by hydrolysis and condensation of acryl alkoxy silane, and the acryl silica particles have acryl groups. The types of acryl alkoxy silane are as described above and are not described here in detail. In some embodiments, the acryl silica particles are formed by hydrolysis and condensation of monoacryl alkoxy silane; in some specific examples, the acryl silica particles are formed by hydrolysis and condensation of MPS. The specific preparation steps of the acryl silica particles include mixing the acryl alkoxy silane with an alcohol solvent and then performing hydrolysis and condensation. The composite additive prepared by the hydrolysis and condensation contains not only the acryl silica particles but also the alcohol solvent. The alcohol solvent is, for example, but not limited to, methanol. The reaction conditions of the hydrolysis and condensation are, for example, but not limited to, being carried out at a temperature of 50° C. in a reflux system. In some specific examples, the organic-inorganic composite in the encapsulation glue is the acryl silica particles, and the encapsulation film has a high visible light transmittance.

The amount ratio of the organic-inorganic composite in the encapsulant is not particularly limited and can be any ratio. In some embodiments, based on the total amount of the crosslinked polymer, the acrylate component and the organic-inorganic composite as 100wt%, the amount of the crosslinked polymer ranges from 20wt% to 50wt%, the amount of the acrylate component ranges from 20wt% to 70wt%, and the amount of the organic-inorganic composite ranges from 10wt% to 50wt%. In some specific examples, based on the total amount of the crosslinking polymer, the acrylate component and the organic-inorganic composite as 100wt%, the amount of the crosslinking polymer ranges from 20wt% to 23wt%, the amount of the acrylate component ranges from 29wt% to 51wt%, the amount of the organic-inorganic composite ranges from 27wt% to 50wt%, and the encapsulation film has a lower WVP value.

In some embodiments, since the polymer contains a solvent and the composite additive contains the alcohol solvent or the dispersion medium, the solvent and the alcohol solvent, or the solvent and the dispersion medium can be removed at any stage in the process of preparing the encapsulant, so that the encapsulant is substantially solvent-free. In some specific examples, the polymer, the acrylate component, the photoinitiator and the composite additive are mixed before removing the solvent.

The present invention will be further described with respect to the following embodiments, but it should be understood that the embodiments are merely illustrative and should not be construed as limitations of the implementation of the present invention.

[Example 1] Packaging Film

2.08 g of fluoroethylene-vinyl ether copolymer (brand: Japan DAIKIN, model: ZEFFLE ^® GK570) was heated at 90° C. for 2 hours to remove butyl acetate from the fluoroethylene-vinyl ether copolymer. The fluoroethylene-vinyl ether copolymer was then dissolved in 12 ml of ethyl acetate and stirred for 1 hour to form a copolymer solution. 1.6 g of FIDA was dissolved in 10 ml of ethyl acetate to form an anhydride solution. The copolymer solution and the anhydride solution were crosslinked at 75° C. for 48 hours under a nitrogen atmosphere to form a crosslinked polymer, thereby obtaining a polymer product comprising the ethyl acetate and the crosslinked polymer.

The polymer product is mixed with the acrylate component to form a reaction raw material, wherein the acrylate component is composed of neopentyl glycol diacrylate (abbreviated as NPGDA, brand: TCI, purity: 89%). The reaction raw material is mixed with a photoinitiator (brand: Ciba, model: Irg 184) in a weight ratio of 100:4, and then the ethyl acetate is removed using a vacuum motor (brand: Vacuumer, model: VOP-100) to obtain a packaging adhesive. The packaging adhesive is stored in a sample bottle wrapped with aluminum foil for standby use. In the packaging adhesive, based on the total amount of the cross-linked polymer and the acrylate component as 100wt%, the cross-linked polymer accounts for 30wt% and the acrylate component accounts for 70wt%.

The encapsulation glue was filled into a hollow mold with a diameter of 5 cm and a thickness of 100 μm, and the hollow mold was sandwiched between two PET films. Then, a glass rod was used to extrude one of the PET films in a direction parallel to the hollow mold so that the excess encapsulation glue in the hollow mold was squeezed out of the hollow mold. A high-power UV light box (brand: OPAS, model: Xlite 400Q) was used to photo-cure the encapsulation glue in the hollow mold for 2 minutes, and then one of the PET films was removed and demolded to obtain an encapsulation film with a thickness of 100 μm.

[Examples 2 to 11] Packaging Film

Examples 2 to 11 are used to prepare encapsulation films using a method similar to that of Example 1. The difference between Examples 2 to 11 and Example 1 is that the type and amount of acrylate monomers in the acrylate component are changed as shown in Table 1. In addition to neopentyl glycol diacrylate, other acrylate monomers used are as follows: 1,6-hexanediol diacrylate (abbreviated as HDDA, brand: TCI, purity: 98.0%); 1H,1H,7H-dodecafluoroheptyl acrylate (abbreviated as 12FHA, brand: TCI, purity: 97.0%).

[Example 12] Packaging Film

In a reflux system, 12.5 g of a suspension of silica nanoparticles (brand: Nissan, model: MA-ST-M, dispersion medium: methanol, content of silica nanoparticles: 40 wt%, average particle size of silica nanoparticles: 25 nm) was diluted with 20 ml of methanol, and then 2.5 g of 3-(methacryloyloxy)propyltrimethoxysilane (abbreviated as MPS, brand: ACROS, purity: 98.0%) was added, wherein, based on the total amount of the silica nanoparticles and the MPS being 100 wt%, the amount of the silica nanoparticles accounted for 66.7 wt%, and the amount of the MPS accounted for 33.3 wt%. Next, the MPS and the silicon dioxide nanoparticles are subjected to a modification reaction at 50° C. for 24 hours, so that the MPS performs surface modification on the silicon dioxide nanoparticles to form modified silicon dioxide nanoparticles, thereby obtaining a composite material additive containing the modified silicon dioxide nanoparticles.

The polymer product is prepared by the same method as in Example 1. The polymer product, the acrylate component and the composite additive are mixed to form a reaction raw material, wherein the acrylate component is composed of 1,6-hexanediol diacrylate (HDDA) and 1H,1H,7H-dodecyl acrylate (12FHA). The reaction raw material is mixed with a photoinitiator (brand: Ciba, model: Irg 184) in a weight ratio of 100:4, and then dried in air for 2 days to remove most of the ethyl acetate and the methanol, and then the remaining ethyl acetate and the methanol are removed by the exhaust motor to obtain a packaging glue. The packaging glue is stored in a sample bottle wrapped with aluminum foil for standby use. Thereafter, a packaging film is prepared by the same method as in Example 1. In the encapsulant, based on the total amount of the crosslinked polymer, the acrylate component and the modified silica nanoparticles as 100wt%, the crosslinked polymer accounts for 21.8wt%, the acrylate component accounts for 51wt% (HDDA accounts for 43.7wt% and 12FHA accounts for 7.3wt%), and the modified silica nanoparticles account for 27.2wt%.

[Examples 13 to 18] Packaging Film

Examples 13 to 18 are used to prepare packaging films using a method similar to Example 12. The difference between Examples 13 to 18 and Example 12 is that the amount of the crosslinking polymer, the type and amount of the acrylate monomer in the acrylate component, and/or the amount of the organic-inorganic composite are changed as shown in Table 2.

[Example 19] Packaging Film

In a reflux system, 5 g of MPS was mixed with 20 ml of methanol, and the MPS was hydrolyzed and condensed at 50° C. for 24 hours to form acryl silica particles, thereby preparing a composite additive containing the acryl silica particles.

The polymer product is prepared by the same method as in Example 1. The polymer product, the acrylate component and the composite additive are mixed to form a reaction raw material, wherein the acrylate component is composed of neopentyl glycol diacrylate. The reaction raw material is mixed with a photoinitiator (brand: Ciba, model: Irg 184) in a weight ratio of 100:4, and then dried in air for 2 days to remove most of the ethyl acetate and the methanol, and then the remaining ethyl acetate and the methanol are removed by the vacuum concentrator to obtain a packaging glue. The packaging glue is stored in a sample bottle wrapped with aluminum foil for standby use. Thereafter, a packaging film is prepared by the same method as in Example 1. In the encapsulant, based on the total amount of the crosslinking polymer, the acrylate component and the acryl silica particles being 100 wt %, the crosslinking polymer accounts for 22.5 wt %, the acrylate component accounts for 29.9 wt %, and the acryl silica particles account for 47.6 wt %.

[Examples 20 to 21] Packaging Film

Examples 20 to 21 are used to prepare packaging films using a method similar to Example 19. The difference between Examples 20 to 21 and Example 19 is that the type and amount of acrylate monomer in the acrylate component are changed as shown in Table 2.

Fourier transform infrared spectrometer analysis: Fourier transform infrared spectroscopy (FTIR, brand: PerkinElmer, model: Spectrum 100) was used to analyze the fluoroethylene-vinyl ether copolymer and FIDA used in Example 1, and the crosslinked polymer prepared in Example 1. The obtained FTIR analysis results are shown in Figure 1. And the silica nanoparticles used in Example 12 and the prepared modified silica nanoparticles were analyzed by Fourier transform infrared spectroscopy, and the obtained FTIR analysis results are shown in Figure 2. Referring to the FTIR graph of Figure 1, the crosslinked polymer has a characteristic peak of 3200 cm ^-1 of the COOH functional group, indicating that the fluoroethylene-vinyl ether copolymer and the tetracarboxylic dianhydride are indeed crosslinked to form the crosslinked polymer. Referring to the FTIR graph of FIG. 2 , the modified silica nanoparticles have a characteristic peak of a C=C functional group at 1638 cm ⁻¹ and a characteristic peak of a C=O functional group at 1722 cm ⁻¹ , indicating that the MPS has indeed performed surface modification on the silica nanoparticles to form the modified silica nanoparticles.

Test for reaction with calcium and titanium: An ultrasonic cleaner (brand: KUDOS, model: SK5210HP) was used to ultrasonically clean an ITO glass (brand: FrontMaterials, model: 10-15 Ω/□) with acetone, methanol and isopropanol. Then, a spin coater (brand: Laurell Technologies, model: WS-650-23) was used to spin coat the nickel oxide sol-gel solution onto the surface of the ITO glass at 2500 rpm for 60 seconds, and then annealed at 160°C for 30 minutes in an air atmosphere to form a nickel oxide layer. A calcium titanate layer is disposed on a surface of the nickel oxide layer opposite to the ITO glass. The calcium titanate layer is prepared by mixing methyl ammonium iodide and lead iodide in a molar ratio of 1:1 in a solvent (0.8 ml of dimethylformamide and 0.2 ml of dimethyl sulfoxide) to form a calcium titanate precursor solution. The solution is then coated with the nickel oxide layer by a rotary coater under nitrogen atmosphere. The calcium-titanium precursor solution is spin-coated onto the surface of the nickel oxide layer at 4500 rpm for 30 seconds in an atmosphere, and then the excess solvent is washed away with ether to form a calcium-titanium precursor layer. The calcium-titanium precursor layer is then annealed at 70° C. for 30 seconds and then at 100° C. for 2 minutes to form the calcium-titanium layer containing a calcium-titanium phase. Afterwards, in a glove box, the encapsulation glue of Example 1 was applied to the surface of the calcium-titanium layer, and the calcium-titanium layer was observed for 24 hours to see if there was any color change. If the encapsulation glue reacted with the calcium-titanium layer, the color of the calcium-titanium layer would be yellow or transparent. Examples 2 to 21 were also measured according to the same method as above, and the results are shown in Tables 1 and 2.

Water vapor permeability (WVP): According to the ASTM E96 standard test method, 10 ^cm2 of the packaging film of Example 1 was covered on a container filled with water, and the container was placed in a desiccator (brand: AS ONE, model: RVD300) and the temperature was controlled to be 23°C and the humidity was controlled to be 5%RH. An electronic balance (brand: Precisa, model: XS 245A-SCS) was used to measure the weight of water vapor evaporated from the container every day for 7 consecutive days, and the weight of water vapor was calculated according to "WVP = ", calculate the WVP value of the packaging film of Example 1. Wherein, m is the weight of water vapor, d is the thickness of the packaging film, t is the number of days of measurement, and A is the area of the packaging film. Examples 2 to 21 are also measured according to the same method as above, and the results are shown in Tables 1 and 2.

Visible light transmittance test: Two tapes with a thickness of 50 μm were attached to a quartz substrate in parallel and 1.5 cm apart, and then the packaging glue of Example 1 was dripped onto the quartz substrate between the two tapes. After a PET film was covered on the tapes and the packaging glue of Example 1, the PET film was squeezed with a glass rod so that the excess packaging glue of Example 1 was squeezed out of the quartz substrate. Then, a high-power UV light box (brand: OPAS, model: Xlite 400Q) was used to photo-cure the packaging glue of Example 1 on the quartz substrate for 2 minutes, and then the PET film was removed to obtain a packaging film attached to the quartz substrate. The packaging film attached to the quartz substrate was tested for visible light transmittance using an ultraviolet/visible light spectrometer (UV-vis spectroscopy, abbreviated as UV-Vis, brand: JASCO, model: V-650), and the wavelength range of the visible light transmittance test was 250nm to 800nm. Examples 2 to 21 were also measured according to the same measurement method, and the results are shown in Tables 1 and 2.

Accelerated life test: An ITO glass (brand: FrontMaterials, model: 10-15 Ω/□) was ultrasonically cleaned using acetone, methanol and isopropyl alcohol using the ultrasonic cleaner. Then, a nickel oxide sol-gel solution was spin-coated onto the surface of the ITO glass using the spin coater at 2500 rpm for 60 seconds, and then annealed at 160°C for 30 minutes in an air atmosphere to form a nickel oxide layer. A calcium titanate layer is disposed on a surface of the nickel oxide layer opposite to the ITO glass. The calcium titanate layer is prepared by mixing methyl ammonium iodide and lead iodide in a molar ratio of 1:1 in a solvent (0.8 ml of dimethylformamide and 0.2 ml of dimethyl sulfoxide) to form a calcium titanate precursor solution. The solution is then coated with the nickel oxide layer by a rotary coater under nitrogen atmosphere. The calcium-titanium precursor solution is spin-coated onto the surface of the nickel oxide layer at 4500 rpm for 30 seconds in an atmosphere, and then the excess solvent is washed away with ether to form a calcium-titanium precursor layer. The calcium-titanium precursor layer is then annealed at 70° C. for 30 seconds and then at 100° C. for 2 minutes to form the calcium-titanium layer containing a calcium-titanium phase. Thereafter, the packaging glue of Example 19 is coated on a surface of the calcium-titanium layer opposite to the nickel oxide layer, a piece of glass is covered on the surface of the packaging glue of Example 19, and a UV-A lamp (brand: ANALYTIK JENA, model: UVLMS-38) is used to perform a photocuring reaction on the packaging glue of Example 19 at a wavelength of 365 nm with a power of 1.5 W to form a packaging film, thereby obtaining a calcium-titanium solar cell including the packaging film. The calcium-titanium solar cell was placed in a constant temperature and humidity oven (brand: Terchy, model: HRMB-80) at a temperature of 65°C and a humidity of 65%RH for 400 hours for accelerated life test. The battery was also tested with a solar simulator (brand: Newport, model: LSH-7320) and a power meter (brand: Keithley, model: 2410) to test the efficiency of the calcium-titanium solar cell, and calculate the normalized efficiency at the tth hour of the accelerated life test according to "normalized efficiency = efficiency of the calcium-titanium solar cell at the tth hour of the accelerated life test / efficiency of the calcium-titanium solar cell at the 0th hour of the accelerated life test", and the results are shown in Figure 3. If the normalized efficiency of the calcium-titanium solar cell is above 0.6, it is considered to be usable. If the normalized efficiency of the calcium-titanium solar cell is less than 0.6, it is considered to be unusable. If the normalized efficiency of the calcium-titanium solar cell is above 0.8 after 400 hours, it is considered to have an excellent lifespan.

Table 1 Embodiment 1 2 3 4 5 6 7 8 9 10 11 Cross-linked polymer (wt%) 30 30 30 30 30 30 30 30 30 30 30 Acrylate component NPGDA (wt%) 70 0 0 0 0 52.5 35 17.5 65 60 50 HDDA (wt%) 0 70 65 60 50 17.5 35 52.5 0 0 0 12FHA (wt%) 0 0 5 10 20 0 0 0 5 10 20 Does it react with calcium and titanium? no no no no no no no no no no no WVP (g⸱mm/m ² ⸱ day) 1.67 2.08 1.69 1.21 2.14 1.26 1.89 1.86 2.43 2.69 2.82 Visible light transmittance (%) 96.9 96 95.6 93.7 91.4 94.2 97.5 96.9 96.4 96.6 96.0

Table 2 Embodiment 12 13 14 15 16 17 18 19 20 twenty one Crosslinked polymer (wt%) 21.8 21.8 20.5 20.5 21.7 21.7 21.7 22.5 22.5 22.5 Acrylate component NPGDA (wt%) 0 38.2 0 35.9 29.0 0 21.8 29.9 0 22.4 HDDA (wt%) 43.7 12.8 41.0 12.0 0 24.9 7.2 0 25.6 7.5 12FHA (wt%) 7.3 0 6.9 0 0 4.1 0 0 4.3 0 Organic-inorganic composites Modified silica nanoparticles (wt%) 27.2 27.2 31.6 31.6 49.3 49.3 49.3 - - - Acrylic silica particles (wt%) - - - - - - - 47.6 47.6 47.6 Does it react with calcium and titanium? no no no no no no no no no no WVP (g⸱mm/m ² ⸱day) 1.97 1.00 1.26 0.85 1.67 1.01 1.14 2.09 1.80 1.31 Visible light transmittance (%) 54.4 58.8 75.0 87.1 89.4 84.5 88.8 96.2 96.7 86.0 Note: The differences in the modified silica nanoparticles used in Examples 12 to 18 are shown in Table A below. The differences lie in the changes in the amounts of silica nanoparticles and MPS used in preparing the modified silica nanoparticles. Table A Embodiment 12 13 14 15 16 17 18 Modified Silica Nanoparticles Silica nanoparticles (wt%) 66.7 66.7 50 50 25 25 25 MPS(wt%) 33.3 33.3 50 50 75 75 75

Referring to Table 1, the encapsulation films of Examples 1 to 11 do not react with calcium titanium and have WVP values below 2.82 g⸱mm/m ² ⸱day. The WVP values of Examples 1 to 8 are less than 2.2 g⸱mm/m ² ⸱day. In addition, the visible light transmittance of the encapsulation films of Examples 1 to 11 is higher than 90%, and the visible light transmittance of Examples 1 to 3 and Examples 7 to 11 is even higher than 95%. It is proved that the encapsulation film formed by the encapsulation glue containing the crosslinked polymer and the acrylate component of the present invention not only does not react with calcium titanium, but also has low water vapor permeability and high visible light transmittance.

Referring to Table 2, the encapsulation films of Examples 12 to 21 do not react with calcium titanate and have WVP values below 2.82 g⸱mm/m ² ⸱day, and the WVP values are even less than 2.2 g⸱mm/m ² ⸱day. In addition, the visible light transmittance of the encapsulation films of Examples 15 to 21 is higher than 80%, and the visible light transmittance of Examples 19 and 20 is even higher than 95%. It is proved that the encapsulation film formed by the encapsulation glue comprising the crosslinked polymer, the acrylate component and the organic-inorganic composite material of the present invention does not react with calcium titanate and has low water vapor permeability.

Referring to the accelerated life test diagram of FIG3 , after 400 hours of the accelerated life test, the normalized efficiency of the calcium-titanium solar cell including the packaging film of Example 19 is still maintained above 0.8, indicating that the packaging film of Example 19 can indeed give the calcium-titanium solar cell a long service life.

In summary, the present invention uses the encapsulating glue to make the encapsulating film formed by the encapsulating glue not react with calcium titanium ore and has low water vapor permeability (WVP value is below 2.82 g⸱mm/m ² ⸱day). Therefore, the purpose of the present invention can be achieved.

However, the above is only an embodiment of the present invention and should not be used to limit the scope of implementation of the present invention. All simple equivalent changes and modifications made according to the scope of the patent application of the present invention and the content of the patent specification are still within the scope of the present patent.

Other features and effects of the present invention will be clearly presented in the embodiments with reference to the drawings, wherein: FIG. 1 is an FTIR graph illustrating the FTIR analysis results of the fluoroethylene-vinyl ether copolymer of Example 1, the tetracarboxylic dianhydride of Example 1, and the crosslinked polymer of Example 1; FIG. 2 is an FTIR graph illustrating the FTIR analysis results of the silica nanoparticles of Example 12 and the modified silica nanoparticles of Example 12; and FIG. 3 is a data graph illustrating the accelerated life test results of a calcium-titanium solar cell including the encapsulation film of Example 19.

Claims (10)

A packaging glue comprises: a crosslinked polymer formed by crosslinking a fluoroethylene-vinyl ether copolymer and a tetracarboxylic dianhydride, wherein the fluoroethylene-vinyl ether copolymer has a weight average molecular weight in the range of 10,000 to 50,000 and a hydroxyl value in the range of 40 mg KOH/g to 170 mg KOH/g, and the tetracarboxylic dianhydride has In the structure shown in FIG. 1 , R represents a tetravalent group containing fluorine and an aromatic group; an acrylate component, comprising at least one acrylate monomer selected from the group consisting of a monoacrylate monomer, a monomethacrylate monomer, a diacrylate monomer, a dimethacrylate monomer, a triacrylate monomer and a trimethacrylate monomer; and a photoinitiator. The encapsulant as claimed in claim 1, wherein the fluoroethylene-vinyl ether copolymer is at least one selected from the group consisting of tetrafluoroethylene-vinyl ether copolymer and chlorotrifluoroethylene-vinyl ether copolymer. The packaging glue as described in claim 1, wherein the commercially available product of the fluoroethylene-vinyl ether copolymer is selected from at least one of the group consisting of ZEFFLE ^® GK570 of DAIKIN of Japan and LUMIFLON ^® LF200 of AGC of Japan. The encapsulant as claimed in claim 1, wherein the tetracarboxylic dianhydride is selected from and 4,4′-(hexafluoroisopropylidene)diphthalic acid. The encapsulant as claimed in claim 1, wherein the acrylate monomer is at least one selected from the group consisting of 2-phenoxyethyl acrylate, 1H,1H,7H-dodecyl acrylate, neopentyl glycol diacrylate, 1,6-hexanediol diacrylate and trihydroxymethylpropane triacrylate. The encapsulant as claimed in claim 1, wherein, based on the total amount of the crosslinking polymer and the acrylate component being 100 wt%, the amount of the crosslinking polymer used ranges from 20 wt% to 80 wt%, and the amount of the acrylate component used ranges from 20 wt% to 80 wt%. The encapsulant as described in claim 1 further comprises an organic-inorganic composite material selected from at least one of the group consisting of modified silica nanoparticles and acryl silica microparticles, wherein the modified silica nanoparticles are formed by surface modification of silica nanoparticles by acryl alkoxy silane, and the acryl silica microparticles are formed by hydrolysis and condensation of acryl alkoxy silane. The encapsulant as claimed in claim 7, wherein the acrylalkoxysilane is at least one selected from the group consisting of monoacrylalkoxysilane, monomethacrylalkoxysilane, diacrylalkoxysilane and dimethacrylalkoxysilane. The encapsulant as described in claim 7, wherein, based on the total amount of the cross-linking polymer, the acrylate component and the organic-inorganic composite being 100wt%, the amount of the cross-linking polymer is in the range of 20wt% to 50wt%, the amount of the acrylate component is in the range of 20wt% to 70wt%, and the amount of the organic-inorganic composite is in the range of 10wt% to 50wt%. A packaging film formed by subjecting the packaging adhesive as described in any one of claims 1 to 9 to a photocuring reaction.

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